Conventional robots are designed to do exactly the same thing over and over again, such as in an assembly line for assembly. These robots are programmed and configured to repeat a given motion to perform a specific function. Robots are often implemented to perform a lot of functions, more efficiently, and often more precisely than humans.
Conventional robots, typically, include one or two robotic arms. These robotic arms can have multiple segments that help facilitate movement in differing degrees of freedom (DOF). Some conventional robots employ a computer to control the segments of the robotic arm by activating rotation of individual step motors connected to corresponding segments. Other designs may use hydraulics or pneumatics to actuate movement in the arm segments. Computers allow precise, repeatable movements of the robotic arm.
Prior Selectively Compliant Articulated Robot Arm (SCARA) robots operate with 4 or fewer degrees of freedom (“DOF”). In other words, these robotic arms are designed to move along 4 or fewer axes. A typical application for a conventional robotic arm is that of pick-and-place type machine. Pick-and-place type machines are used for automation assembly, automation placing, printed circuit board manufacturing, integrated circuit pick and placing, and other automation jobs that contain small items, such as machining, measuring, testing, and welding. These robotic arms include an end-effector, also known as robotic peripheral, robotic accessory, robot or robotic tool, end of arm (EOA) tooling, or end-of-arm device. The end-effector may be an implement such as a robotic gripper, press tool, paint gun, blowtorch, deburring tool, arc welding gun, drills, etc. These end-effectors are typically placed at the end of the robotic arm and are used for uses as described above. One common end-effector is a simplified version of the hand, which can grasp and carry different objects. Such end effectors typically support maximum payloads ranging from 3 kg-20 kg (6.61-44.09 pounds).
Another type of robot that has been implemented in positioning of a radiation source of a radiation treatment system includes an articulated robotic arm for positioning a radiation source, such as a linear accelerator (LINAC), mounted at a distal end of the articulated robotic arm, for selectively emitting radiation, such as described below in FIG. 1A.
FIG. 1A is a schematic block diagram illustrating a conventional treatment delivery system 100. The depicted treatment delivery system 100 includes a radiation source 103, in the form of a linear accelerator (LINAC), and a treatment couch 106, as described above. The treatment delivery system 100 also includes multiple imaging x-ray sources 107 and detectors 108 (e.g., cameras). The two x-ray sources 107 may be nominally aligned to project imaging x-ray beams through a patient from at least two different angular positions (e.g., separated by 90 degrees, 45 degrees, etc.) and aimed through the patient on the treatment couch 106 toward the corresponding detectors 108 or to a single large imager. The x-ray imaging system generates image data representative of one or more real time or near real time images that show the position and orientation of the target in a treatment coordinate frame. The treatment delivery system 100 may be an image-guided, robotic-based radiation treatment system (e.g., for performing radiosurgery) such as the CyberKnife® system developed by Accuray, Inc. of Sunnyvale, Calif.
In the illustrated embodiment, the LINAC 103 is mounted on a robotic arm 102. The LINAC 103 is used to produce a beam of radiation that can be directed to a target. The robotic arm 102 is a highly articulated robotic arm that may have multiple (e.g., 5 or more) rotational degrees of freedom in order to properly position the LINAC 103 to irradiate a target such as a pathological anatomy with a beam delivered from many angles in an operating volume around the patient. The treatment implemented with the treatment delivery system 100 may involve beam paths with a single isocenter (point of convergence), multiple isocenters, or without any specific isocenters (i.e., the beams need only intersect with the pathological target volume and do not necessarily converge on a single point, or isocenter, within the target). Furthermore, the treatment may be delivered in either a single session (mono-fraction) or in a small number of sessions (hypo-fractionation) as determined during treatment planning. The treatment delivery system 100 delivers radiation beams according to the treatment plan without fixing the patient to a rigid, external frame to register the intra-operative position of the target volume with the position of the target volume during the pre-operative treatment planning phase.
In addition, the treatment delivery system 100 may include a controller 101 that may implement algorithms to register images obtained from the imaging system (e.g., imaging x-ray sources 107 and detectors 108) with pre-operative treatment planning images obtained from a diagnostic imaging system in order to align the patient on the treatment couch 106 within the treatment delivery system 100. Additionally, these images may be used to precisely position the radiation source 103 with respect to the target volume or target. The controller 101 may contain treatment planning and delivery software, which may be responsive to pre-treatment scan data CT (and/or MRI data, PET data, ultrasound scan data, and/or fluoroscopy imaging data) and user input, to generate a treatment plan consisting of a succession of desired beam paths, each having an associated dose rate and duration at each of a fixed set of treatment positions or nodes. In response to the controller's directions, the robotic arm moves and orients the x-ray LINAC 103, successively and sequentially through each of the nodes, while the x-ray LINAC 103 delivers the required dose as directed by the controller 201. The pre-treatment scan data may include, for example, CT scan data, MRI scan data, PET scan data, ultrasound scan data, and/or fluoroscopy imaging data. Prior to performing a treatment on a patient treatment couch 106, the patient's position and orientation within the frame of reference established by imaging system must be adjusted to match the position and orientation that the patient had within the frame of reference of the CT (or MRI or PET or fluoroscopy) scanner that provided the images used for planning the treatment.
The treatment couch 106 may be a conventional treatment table, such as the AXUM® treatment couch developed by Accuray, Inc. of Sunnyvale, Calif.
Another conventional treatment delivery system is a gantry-based (isocentric) intensity modulated radiotherapy (IMRT) system, in which a radiation source 103 (e.g., a LINAC) is mounted on the gantry in such a way that it rotates in a plane corresponding to an axial slice of the patient. Radiation may be delivered from several positions on the circular plane of rotation. Another conventional treatment delivery system is a stereotactic frame system such as the GammaKnife®, available from Elekta of Sweden.
FIG. 1B is a perspective drawing illustrating a workspace of a conventional radiation treatment system 150 including a set of spatial nodes at which to position the radiation source. The radiation treatment system 150 is similar to the radiation treatment system 100 and includes a radiation source 103, detectors 108, imaging sources 108, and a robotic arm 102. The conventional radiation treatment system 150 also includes a treatment couch 106 and a stand 1 10 upon which the treatment couch 106 is disposed.
During radiation treatment, the patient rests on treatment couch 106, which is maneuvered to position a volume of interest (“VOI”) containing a target to a preset position or within an operating range accessible to radiation source 103 (e.g., field of view). The robotic arm 102 has multiple (e.g., six) rotational degrees of freedom capable of positioning the radiation source 103 with a finite number of positions and orientations within its operating envelope.
A collection of spatial nodes and associated safe paths interconnecting these spatial nodes is called a “workspace” or “node set”. FIG. 1B illustrates a workspace 111, including a number of spatial nodes 112 each represented by a “+” symbol (only a couple are labeled). Multiple different workspaces may be created and defined for different patient work areas. For example, workspace 111 may be spherical (as illustrated) and defined for treating VOIs residing within the head of a patient 904. Alternatively, workspace 111 may have other geometries (e.g., elliptical) and defined for treating VOIs residing within other areas of a patient. Additionally, multiple workspaces 111 may be defined for different portions of a patient, each having different radius or source to axis distances (“SAD”), such as 650 mm and 800 mm. The SAD is the distance between the collimator in the radiation source 103 and the target within the VOI. The SAD defines the surface area of the workspace 111. In one embodiment of an elliptical workspace, the SAD may range from 900 mm to 1000 mm. Other SADs may be used.
Spatial nodes 112 reside on the surface of workspace 111. Spatial nodes 112 represent positions where the radiation source 103 is pre-programmed to stop and delivery a dose of radiation to the VOI within the patient. During delivery of a treatment plan, robotic arm 102 moves radiation source 103 to each and every spatial node 112, where a dose is determined to be delivered, following a predefined path. The predefined path may also include some spatial nodes 112 where no dose needs to be delivered, in order to simplify the motions of the robotic arm.
FIG. 1B illustrates a node set including an exemplary number of spatial nodes 112 (e.g., 100 to 115). The node set may include spatial nodes 112 substantially uniformly distributed over the geometric surface of workspace 111. The node set includes all programmed spatial nodes 112 and provides a workable number of spatial nodes 112 for effectively computing treatment plan solutions for some ailments and associated VOIs. The node set provides a reasonably large number of spatial nodes 112 such that homogeneity and conformality thresholds can be achieved for a large variety of different VOIs, while providing enough vantage points to avoid critical structures within patients. It should be appreciated that the node set may include more or less spatial nodes 112 than is illustrated or discussed. For example, as processing power increases and experience gained creating treatment plans, the average number of spatial nodes 112 may increase with time to provide greater flexibility and higher quality treatment plans.
In addition to being limited in the spatial nodes due to obstructions and mechanical limitations of the conventional robotic arms, the conventional robotic arms can not be used in some treatments, such as posterior treatments due to these obstructions and mechanical limitations. Also, the conventional robotic arms may have complex paths that are calculated during treatment planning. The paths calculated are complex because all the DOF are rotational DOF. In order to position the LINAC in 3D space using only rotational DOF, most or all of the rotational axes need to be rotated to position the LINAC. For example, in order to move the LINAC a certain distance along a single axis in the 3D space, multiple axes may have to be rotated to move the LINAC to the position that is the certain distance on the single axis.